Fluid flow energy extraction system and method related thereto

ABSTRACT

Disclosed is a system and method for both consumer and utility scale energy extraction from flow-based energy sources. The passive system may utilize directing perforations on a surface in order to create and air jet vortex generators. Alternatively the system may provide for flow through discrete orifices aligned with the span of an aerodynamic assembly in a co-flow direction, utilizing a Coanda effect. Further additional configurations include directing flow through a perforated surface skin that is near the trailing edge on the suction side. Even further are embodiments for blowing air directly out of the trailing edge of an airfoil. The disclosed systems and methods support a wide variety of scenarios for fluid flow energy extraction, such as wind or water flow, as well as for related products and services.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase filing of PCT/US2015/053002, filedon Sep. 29, 2015, entitled “Fluid Flow Energy Extraction System andMethod Related Thereto” which claims priority to provisional U.S. PatentApplication Ser. No. 62/057,325, filed on Sep. 30, 2014, entitled “FluidFlow Energy Extraction Systems and Methods Related Thereto” which suchapplications are commonly assigned to the Assignee of the presentinvention and which disclosures are hereby incorporated herein byreference in their entirety for all purposes.

This application includes material that is subject to copyrightprotection. The copyright owner has no objection to the facsimilereproduction by anyone of the patent disclosure, as it appears in theWorld Intellectual Property Office or United States Patent and TrademarkOffice files or records, but otherwise reserves all copyright rightswhatsoever.

TECHNICAL FIELD

The present invention relates in general to the field of energyextraction. In particular, the system provides for both consumer andutility scale energy extraction from flow-based energy sources. Thedisclosed systems and methods support a wide variety of scenarios forfluid flow energy extraction, such as wind or water flow, as well as forrelated products and services.

STATEMENT OF FEDERALLY FUNDED RESEARCH

None.

BACKGROUND OF THE DISCLOSURE

Wind energy, the process by which wind is exploited to generateelectrical power, has shown tremendous promise. Wind energy systems donot produce greenhouse gas emissions during production and do notconsume any water for cooling. This, coupled with the fact that, in somelocations, the “cost of electricity from wind is comparable to that fromconventional fossil-fueled power plants” makes wind a provider of cleanenergy at an economic price. However, the large mass of machineryrequired in wind energy systems results in a high cost of materials.Also, the placement of the machinery at such a height results in tediousand expensive maintenance. Additionally, the noise pollution, potentialwildlife threat, land mass use, and lack of aesthetic appeal associatedwith wind energy systems can be unfavorable.

Conventional wind energy systems deploy rather larger masses ofmachinery high up in the air on tall towers in order to extract windpower efficiently using large rotor blades. This adds weight to the topof the system and imposes a relatively high materials usage in themachinery, tower and foundation. Furthermore, the large rotors arefragile systems, which need to be made from high performance composites.Their rotation can have a number of unintended side effects such asinteraction with wild life, throwing ice accumulation, lightningattraction and many other issues. In addition the maintenance of thesystem is difficult as it has to be done at height. These types ofproblems become more significant when turbines are installed close topopulation centers or directly on buildings. Conventional orunconventional water flow extraction systems (tidal, river or similarsystems) in the renewable energy fields pose very similar sets ofproblems.

There have been efforts to address alternative, or unconventionalflow-based energy extraction systems. In 1953 De Havilland PropellersLtd. build a 100 kW wind turbine in St. Albans (Prince, 2006), UK basedon the Andreau-Enfield wind turbine principle (Andreau, 1946). Later, in1957 the Algerian Gas and Electricity Company build a similar turbine atGrand Vent (Delafond, 1961). Both turbines had a diameter of 24 meters.The Andreau-Enfield turbine is driven by a hollow wind turbine blade, inwhich airflow is allowed to exit the tip of the blade. The flow insidethe blade is driven by the centrifugal force, essentially having thewhole rotor operating a centrifugal pump. The pump draws the air fromthe base of the tower, where airflow passes a fan which extracts power.

The performance drawback comparing this concept to a modern day windturbine is obviously that there are a series of losses associated withthe system. Nevertheless, Ulrich Hutter reported in the late 1960's apower curve which is surprisingly good showing a system powercoefficient of about 11%. Presumably, this number could be higher, hadthe machine been designed with modern day wind turbine technology(blades and generators), fan technology and duct design. The benefit ofthe design is that the power generating equipment now is placed on theground, making the machine design lighter and allowing for ground-basedservicing of the equipment. However the concept still needs to maintainsystems at the top which controls the rotor blade, both in terms ofpower regulating the rotor and yawing the rotor to face the wind.

Another known wind technology based on ducted wind turbines, also aimsto improve wind energy systems. In these systems, a shroud is used tospeed up the wind in a manner very similar to the venture effect andthen extract the wind energy using a small conventional rotor andgenerator system. Although very attractive, the concept has the samedrawbacks as conventional wind turbines. Further, the structure has tocarry aerodynamic loading from the shroud.

As mentioned, most of the existing wind turbine concepts involve movingblades in the swept area, whereas only few systems do not. One exampleis the EWICON frame, which harvests energy from the wind byelectrostatic discharge being transported through a frame facing thewind. A second concept is the INVELOX system from Sheer wind, whichtakes air in from a conical structure, leading it into a duct where theenergy is extracted by a turbine.

Inversely, the Dyson (2009) and Tokyo Shibaura Electric (1981) air fanssystems are both developed to accelerate ambient air through a ringshaped structure in a household setting. A variant over the concept isfound in De Lisio Salvatore's (1949) invention where multiple rings areused. Other variants of these systems can be found medical venturimasks, industrial dilution blowers with air entrainment, industrial airmovers and many other applications.

Despite efforts to create more efficient and reliable flow energyextraction systems, there are currently no commercially successfulapproaches which limit many of the inherent risks and drawbacks of thetraditional turbine design. It is therefore a need in the art to develophigh performance flow energy extraction systems capable of both consumerand utility-scale energy generation.

SUMMARY OF THE DISCLOSURE

The present invention addresses the limitations of the art by providingthe generation of a high pressure potential of a passive structure. Thiscan be generated with high lift aerodynamic assemblies, such asairfoils. It is well known from the aerospace industry that high liftcan be achieved by blowing air through the surface. Such ideas have beendemonstrated in wind energy, where blowing through the skin of aconventional wind turbine rotor was used to enhance performance.

The present invention provides a solution to all the aforementioneddetriments in the form of a fluid flow energy extraction system that hasno external rotor blades. The system is composed of a self-amplifyingaerodynamic system, and may further comprise one or more airfoils. Thisaerodynamic system extracts the wind energy and is connected to aturbine wheel at the bottom of the system which is in turn connected toa generator.

The fundamental approach of the present invention is to maximize on thegeneration of high pressure potential in a passive structure. This isachieved through the use of aerodynamic assemblies. One example of anaerodynamic assembly is an airfoil. The airfoil is a blade with a spanplaced in a wind flow. The airfoil is angled to the wind; thisorientation creates a low suction pressure on its suction side. A seriesof orifices, or perforations, are placed along the span of the blade.The orifices are placed in a deliberative, calculating manner tomaximize the efficiency of the airfoil performance. There are manyembodiments for the placement of the orifices: they can be placed in across-flow configuration, co-flow configuration, or they can bealtogether replaced with a slit or series of slits.

It is therefore an object of the present invention to increase pressurepotential by angling the orifices to the surface normal in order tocreate a small vortex. This is known as an air jet vortex generator. Itis another object of the present invention to blow the air throughdiscrete orifices or through a slit aligned with the span of the bladein a co-flow direction of the airfoil. This is used in some aircraftswhere high lift is needed, often referred to as the Coanda effect.

It is another object of the present invention to provide a system forenergy extraction from a fluid comprising at least one aerodynamicassembly having a plenum, wherein the aerodynamic assembly furthercomprises one or more perforations on its outer surface; an energyextraction device comprising an inlet and an outlet; and a channelproviding fluid connection between the outlet of the energy extractiondevice and the aerodynamic assembly plenum; wherein fluid flow acrossthe aerodynamic assembly causes a negative inner aerodynamic assemblyplenum pressure (Pi) relative to an ambient pressure (Pa) resulting influid flow through the energy extraction device, into the plenum and outthrough the perforations of the aerodynamic assembly due to the pressuredifferential, Pi-Pa.

The aerodynamic assembly may further comprise one or more airfoilsarranged to generate low pressure regions near the perforations. Anenergy extraction device is connected to an electric generator orhydraulic pump, which may further comprise more than one of an electricgenerator or hydraulic pump. The fluid flow may be water or air.Further, the system may comprise a motor to align the device or parts ofthe device in response to the direction of the fluid flow.

In another aspect, the one or more perforations on the aerodynamicassembly is arranged to amplify the differential pressure (Pi-Pa) asadditional fluid exits the perforations in the surface. Further two ormore aerodynamic assemblies are mirrored to increase centerline pressureand airflow velocity to higher than ambient conditions. The surfaces mayfurther be arranged in a ring shaped configuration.

It is another object of the present invention to provide a converterelectrically coupled to the generator and configured to convert ACvoltage received from the generator to DC voltage. One or moreadditional features may be provided, including comprising at least oneaerodynamic assembly is mounted onto a building structure or mountingthe generator at a level below the roof of the building structure and influid communication to the plenum of the at least one aerodynamicassembly by the channel.

It is another object of the present invention to provide at least oneaerodynamic assembly mounted underwater. Further, the energy extractiondevice of the underwater system may be mounted above water and in fluidcommunication to the plenum of the at least one aerodynamic assembly bythe channel. Thus one half of the aerodynamic assembly is the underwaterbottom surface or comprises of a shape aligned with the underwaterbottom.

It is another object of the present invention to provide a method ofextracting energy from a fluid comprising: positioning at least oneaerodynamic assembly having a plenum, wherein the aerodynamic assemblycomprises one or more perforations on its outer surface, and connectingan energy extraction device comprising an inlet and an outlet using achannel in fluid connection between the outlet of the energy extractiondevice and the aerodynamic assembly plenum, wherein the fluid flowingacross the aerodynamic assembly causes a negative plenum pressure (Pi)relative to the ambient pressure (Pa) resulting in fluid flow throughthe energy extraction device, into the plenum and out through theperforations of the aerodynamic assembly.

In one aspect, the method comprises one or more of the followingfeatures: the aerodynamic assembly further comprises one or moreairfoils arranged to generate low pressure regions near theperforations; the energy extraction device is connected to one or moreof an electric generator or hydraulic pump; a motor to align theaerodynamic assembly in response to the direction of the fluid flow; theone or more perforations on the aerodynamic assembly is arranged toamplify the Pi-Pa pressure differential; at least two aerodynamicassemblies are mirrored to increase centerline pressure and airflowvelocity to higher than ambient conditions; a converter electricallycoupled to the generator and configured to convert AC voltage receivedfrom the generator to DC voltage; at least one aerodynamic assemblymounted onto a building structure; the energy extraction device ismounted at a level below the roof of the building structure in fluidcommunication to the plenum of the at least one aerodynamic assembly bythe channel; at least one aerodynamic assembly mounted underwater andwherein the energy extraction device is mounted above water and in fluidcommunication to the plenum of the at least one aerodynamic assembly bythe channel.

There are however, other methods which can effectively produce higherairfoil performance. It is therefore another object of the presentinvention to provide a system for blowing through a perforated surfaceskin, made effective when it is near the trailing edge on the suctionside. It is yet another object of the present invention to have airblowing directly out of the trailing edge of the airfoil. Indeed, thepresent invention allows the wind extraction to take place within theairfoils, thus removing the need for the external rotor blades. Thispresent invention decreases noise pollution, land mass use, and wildlifethreat. Additionally, the present invention effectively and economicallyplaces all the relevant heavy machinery (turbine and generator) at theground level of the disclosed embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of thedisclosure will be apparent from the following description ofembodiments as illustrated in the accompanying drawings, in whichreference characters refer to the same parts throughout the variousviews. The drawings are not necessarily to scale, emphasis instead beingplaced upon illustrating principles of the disclosure:

FIG. 1 depicts a diagram of a two-dimensional representation of fluidflowing around one aerodynamic assembly having a plenum.

FIG. 2 depicts a diagram of a simple-form of the present invention,having one airfoil, on duct, and one energy extraction device.

FIG. 3 depicts a schematic of a mosaic of differing skin flows andaccompanying perforations or orifices.

FIG. 4 depicts a schematic of two opposing, or mirrored, airfoilconfigurations on an axis capable of being turned into fluid flows.

FIG. 5 depicts a chart illustrating paired airfoil performance as afunction of distance.

FIG. 6 depicts an embodiment with two opposing airfoils showing air jetsarranged in the preferred arrangement with elongated perforations (ovalor square or similar) arranged counter oriented (also having an angle tothe surface normal).

FIG. 7A depicts a simple arrangement of an aerodynamic device pairedwith a house roof top wherein the roof is acting as part of the oppositeairfoil.

FIG. 7B depicts an elevational view of the aerodynamic system pairedwith a house roof top.

FIG. 8 depicts a ring arrangement of the present invention. Air jets areshown only with one swirl direction.

FIG. 9 depicts a cross sectional view showing air intake at the base ofa tower.

FIG. 10 depicts a fundamental principle of taking advantage of the lowpressure in an expanding wake. The disc in the middle represents anobstruction, with air inlet from ambient pressure, wherein the linesindicate the expanding wake.

FIG. 11 depicts a radial version (based on entrainment and wakeexpansion) of the present invention.

FIG. 12 depicts a linear version of FIG. 11 having mirrored aerodynamicassemblies, wherein an inner plenum is shown.

FIG. 13 depicts an embodiment of the present invention having astaggered array of airfoils (left cross section)

FIG. 14 depicts a cross section of a staggered asymmetrical array of thepresent invention with accompanying fluid flow.

FIG. 15 depicts computational fluid dynamic (CFD) calculation in twodimensions showing airflow between two opposite airfoils and a flowbeing injected into the stream from the hollow of the airfoils.

FIG. 16A depicts the power extracted in Watt per meter airfoil and thecorresponding power coefficient calculated as a function of the pressuredifferential between the hollow of the airfoils and the ambientpressure.

FIG. 16B depicts a measurement of power extracted in percentage ofefficiency of the airfoil and the corresponding power coefficient.

DETAILED DESCRIPTION OF THE DISCLOSURE

While the making and using of various embodiments of the presentinvention are discussed in detail below, it should be appreciated thatthe present invention provides many applicable inventive concepts thatcan be embodied in a wide variety of specific contexts, goods, orservices. The specific embodiments discussed herein are merelyillustrative of specific ways to make and use the disclosure and do notdelimit the scope of the disclosure.

All publications and patent applications mentioned in the specificationare indicative of the level of skill of those skilled in the art towhich this disclosure pertains. All publications and patent applicationsare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, which form a part hereof, andwhich show, by way of illustration, specific example embodiments.Subject matter may, however, be embodied in a variety of different formsand, therefore, covered or claimed subject matter is intended to beconstrued as not being limited to any example embodiments set forthherein; example embodiments are provided merely to be illustrative.Likewise, a reasonably broad scope for claimed or covered subject matteris intended. Among other things, for example, subject matter may beembodied as methods, devices, components, or systems. The followingdetailed description is, therefore, not intended to be taken in alimiting sense.

Throughout the specification and claims, terms may have nuanced meaningssuggested or implied in context beyond an explicitly stated meaning.Likewise, the phrase “in one embodiment” as used herein does notnecessarily refer to the same embodiment and the phrase “in anotherembodiment” as used herein does not necessarily refer to a differentembodiment. It is intended, for example, that claimed subject matterinclude combinations of example embodiments in whole or in part.

In general, terminology may be understood at least in part from usage incontext. For example, terms, such as “and”, “or”, or “and/or,” as usedherein may include a variety of meanings that may depend at least inpart upon the context in which such terms are used. Typically, “or” ifused to associate a list, such as A, B or C, is intended to mean A, B,and C, here used in the inclusive sense, as well as A, B or C, here usedin the exclusive sense. In addition, the term “one or more” as usedherein, depending at least in part upon context, may be used to describeany feature, structure, or characteristic in a singular sense or may beused to describe combinations of features, structures or characteristicsin a plural sense. Similarly, terms, such as “a,” “an,” or “the,” again,may be understood to convey a singular usage or to convey a pluralusage, depending at least in part upon context. In addition, the term“based on” may be understood as not necessarily intended to convey anexclusive set of factors and may, instead, allow for existence ofadditional factors not necessarily expressly described, again, dependingat least in part on context.

The present invention is described below with reference to diagrams,drawings, block diagrams and operational illustrations of methods andprocedures. It is understood that each block of the block diagrams,drawings, or operational illustrations, and combinations of blocks inthe block diagrams, drawings, or operational illustrations, can beimplemented by means of executed steps or by hardware and computerprogram instructions, or by other automated means.

The embodiments described herein may be embodied in many differentforms. In its principal form, the invention comprises of one aerodynamicassembly. Turning to FIG. 1, an exemplary embodiment 100 is presented.The aerodynamic assembly 105 may be an airfoil. The airfoil 105 isfurther embodied to be angled to the wind to create a suction pressureon its suction side, to be described by the non-dimensional number, Cp.The pressure from the flow 102, represented as U_(∞), drives airflow104, represented as U_(j), through the skin of the surface of theaerodynamic assembly originating from one or multiple perforations ofthe skin of the airfoil 104, leaving a pressure inside the airfoilplenum 101, referred to as Pi. It is the plenum pressure, Pi, which isused to drive an energy extraction. The plenum 101, which refers to theinside chamber of the aerodynamic assembly, is then connected to theatmospheric, or ambient, pressure, Pa, through a channel. The principlemay further be represented as Pa+0.5*p*Cp*U_(∞) ²,

In a fundamental embodiment of the present invention, an aerodynamicassembly, referred to further herein as an airfoil, with a span isplaced in a wind flow. A series of orifices, or perforations, is placedalong the span of the blade to allow for the beneficial flow to occurthrough the skin. The orifices are placed in such a way that the flowthrough the orifices will assist the efficiency of the airfoilperformance. The configuration can be in a cross flow or co-flowconfiguration. It is also possible the orifices are replaced with a slitor a series of slits (Coanda type arrangement). In another embodimentthe air is blown directly out of the trailing edge of the blade. Inanother embodiment the skin of the airfoil is perforated. As the windpasses the blade, the low pressure on the suction side drives thegeneration of an inner plenum pressure, Pi. Connecting the plenum via achannel to the atmospheric pressure, Pa, a flow through the channel isgenerated into the plenum and out through the airfoil skin. The totalairflow through the channel is determined by the total volume flowthrough the skin:

Vt=Sum(Aj*Uj),[1,N],

where Aj is the area of skin perforation and Uj is the average velocity.If a fan and motor is placed in the channel, energy can be extractedfrom the airflow, Vt. The energy extracted is proportional to theairflow through the fan, the pressure drop over the fan, but no morethan (Pa−Pi), and the efficiency of the fan. FIG. 2 shows an exemplaryairfoil assembly 204 in fluid communication with the ambient pressure Pa205. This pressure differential creates a flow through the channel 207that is directed towards the plenum 202 and out through the orifices203, as the direction and shape of the airfoil 204 allows for fluid flow201 to create a pressure differential (Pa−Pi). By placing a fan, motor,and generator, collectively referred to as an electric generator 206, inthe strategically-placed channel 207, which is in fluid communicationwith the plenum 202, energy can be extracted. In another embodiment, thechannel may lead to a hydraulic pump. In yet another embodiment, thechannel comprises combinations of one or more electric generators or oneor more hydraulic pumps.

Turning to FIG. 3, an aerodynamic device 300 describing varyingalternatives of perforations 302, 303 is provided. Fluid flow 301 drivesthe airflow 305 into a channel 307 in fluid communication with theplenum 308. The various perforations 302, 303 have the airflow drawnthrough. The Pa−Pi pressure differential the airflow 305 driven throughthe channel 307 actuates the electric generator 306, resulting in energyextraction. A trailing edge blowing 304 may further allow for a Coandaeffect to occur in connection with the skin perforation 302.

Different versions of skin flows may be desirable, as the one-airfoilconfiguration shown in FIGS. 2-3 may result in additional efficiency andstructural issues. Although the simple form shown in FIG. 2 is possibleto realize, it is noted by Oliver et al. 1997, in a wind tunnel effectduring testing of a regular airfoil. The effect in their test with 35m/s wind and an area of 0.78 m2 produces less than 34 watts of effectcorresponding of a power coefficient of about 1%. Considering that theobjective of an aerodynamic performance of this kind enhancementnormally is to minimize the flow through the skin, which in termsreduces the power and the efficiency for energy extraction. Also, it isdetermined to be a less efficient way of implementing the presentinvention, the most important reason being that it may prove difficultto realize sufficient low pressure build-up on the suction side of theairfoil with a single airfoil. Secondly, the single airfoilconfiguration is very sensitive to facing of the fluid flow veryaccurately, i.e. it needs to be in a narrow angle of attack with thewind direction, corresponding to the maximum lift and thus suctionpressure.

Placing two airfoils mirrored to each other produces several additionaladvantages. First of all the pressure at the surface of each respectiveairfoil can be more than 20 times higher than it otherwise would be,before the flow breaks down and stop working due to viscous forces inthe fluid, especially when placed very close together (see FIG. 5). Inan exemplary embodiment, the airfoil used in FIG. 5 as an example is aNACA634XX which was made 20% thick. The large thickness was chosen toemphasize that plenty of room can be made available in the plenum forinternal airflow while also offering structural advantage. Secondly thecenterline pressure and airflow velocity will be significantly higherthan ambient conditions even when the airfoils are not close togetherand the sensitivity to the wind direction is significantly reduced.Thus, it the present invention describes the overall potential of thestructure to extract energy as the secondary airflow is injected fromthe ambient pressure. The paired set offers structural advantages, whenone considers the structure sitting passively through storms and mayexperience side winds. A model of 2*0.015 m2, would at 15 m/s be able toeasily produce 14 W per meter length, corresponding to an efficiency of20% or about 430 W/m2 surface area with jets.

An important aspect of the present invention is that the flow throughthe skin, the surface of the aerodynamic assembly, for example by airjets, will enhance the airfoil performance. The higher the airflow, thebetter the airfoil performance. In principle, if the system was frictionfree, this is a completely self-amplifying concept. The more air flowingthrough the skin, the stronger the performance of the system. Comparedto a shrouded or ducted wind turbine, these exhibit the same airflowacceleration, when the rotor is not engaged. However, one the rotorengages this chokes the effect of the shroud, rather than amplifying itas in the present invention.

FIG. 4 shows a further embodiment of the present invention to employ atwo-airfoil mirrored system with a yaw motor that allows the system torotate in response to the direction of the wind, where the ambientpressure and air intake is at the bottom of a tower, passing through thepower generating fan, divides into the two opposite airfoils and intothe free stream driven by the low pressure. A dual airfoil assembly 400provides two airfoils 401 in a mirrored arrangement. The airfoils havinga plenum and various perforations (not shown) in a mirror-like fashion.The fluid flow path 402 is directed in between the airfoils 408, anddriven through the assembly 400. The assembly may be rotated 405 fordirectional alignment with the fluid flow 402. This may be accomplishedby mechanical actuation such as a yaw motor 407 actuating upon an axis403. The axis 403 may further act as the channel in fluid communicationbetween the atmosphere 404 and the plenum of each airfoil. An electricgenerator 406 is placed within the channel 403. It is another embodimentof the present invention to provide two opposing airfoils that extractthe wind are connected to the turbine wheel at the base, thus beingself-amplifying—the stronger the airflow through the jets, the lower thepressure to drive them. Regulating the maximum power is achievablesimply in this configuration by a simple actuated air choke located atany point along the flow path. This is a much simpler and safer way toregulate the power, compared to normal wind turbines which are dependenton the generator to be connected to the grid in order to maintain a saferotor speed. The airfoil arrangement would preferably sit on a motorizedarrangement that aligns the system with the incoming wind as with FIG.4.

FIG. 6 provides an optimized arrangement of the present invention 600,wherein optimal air jet vortex generators are utilized 604. Mirroredaerodynamic assemblies 602 are positioned to utilize the amplificationcharacteristics described above. A machine of this size is capable oflarge sizes. The exemplary embodiment of FIG. 6 is 20 meters tall and achord of 1 meter, and produces about 9 kW @ 15 m/s wind speed withoutany form of further design optimization.

In another embodiment, the proposed technology can be integrated intobuildings in a more aesthetically pleasing manner and can be integratedinto a house roof, as show in FIG. 7. FIG. 7A shows a perspective viewof a house structure having an aerodynamic assembly 701 positionedparallel to the apex of a roof 702. The roof 702 acts part of theopposite airfoil. A channel 705 provides fluid communication with anelectric generator 704 having an inlet 703 and an outlet into thechannel 705. Perforations in the basal portion of the aerodynamicassembly 701 cause the ambient airflow to cause a pressure differentialbetween the plenum and roof 702. In this system 700, the airflow comesthrough the air intake at the bottom and out through the gap between theairfoil and the house roof. In FIG. 7, the roof acts as the oppositeairfoil and the gap between the airfoil and roof corresponds to theorifices in the embodiment of FIG. 3 and the elongated slits in theembodiment of FIG. 4 and FIG. 6. The airflow comes through the airintake at ground level, passes the generator and its fan, up on top intothe airfoil and out through the gap between the airfoil and the houseroof. Placing the generator at ground level removes the vibrationproblems usually associated to wind turbines on houses. The airflowcomes through the air intake 703 at ground level, passes the generatorand its fan 704, up through the channel 705 on top into the airfoil 701and out through the gap between the airfoil and the house roof 702. Itis very likely that in order to optimize this application, and dependingon the roof top shape, airflow would also be needed to come out of theroof top, or by pipes placed on the roof top with gaps. Placing thegenerator at ground level removes the vibration problems usuallyassociated to wind turbines on houses. Specifically for thisarrangement, there is a relatively large wind direction acceptance,despite the limitations of the house turning towards the wind direction.For many regions around the world, there is a prevailing wind direction,so the only requirement is that the house is arranged perpendicular tothe prevailing wind direction to maintain effect.

The embodiment illustrated in FIG. 7, provides an efficientconfiguration for river and ocean currents, which are oftenuni-directional or bi-polar in direction, where the house is replacedwith a bottom mounted structure. One preferred solution is to continueto utilize a pair set of airfoils, i.e. FIG. 6 turned 90 degrees andparallel with the bottom mounted with a tripod in each end. For a 20meter long device, the energy extraction would be about 360 kW at acurrent of 3 m/s.

FIG. 8 constitutes a ring arrangement of the present invention. Here theairfoils are not placed opposite, i.e. suction side against suction sidesuch as in FIG. 6 and FIG. 7, but rather in tandem as a classic pair offlapped airfoils. Also in this embodiment the airfoils are not paired asthey are in the two opposite airfoil case (FIG. 6), as this concepttakes further advantages of amplifying the wake expansion by displacingas much as possible tangentially after passing the turbine. The airfoils801, 802 are able to utilize the presence of the inner ring, in the caseof the outer ring 802, or the opposing ends of the ring arrangement, inthe case of the inner ring 801, for amplification effect. Perforations805 are thus located on the inside (suction) side of each airfoil 801,802. Fluid flow 806 passes through the assembly, which draw from thechannel 803 into the plenum of each ringed airfoil 801, 802 activatingthe electric generator (not shown) in the channel 803.

FIG. 9 constitutes a simpler variant of the embodiment shown in FIG. 8,wherein a tower continues into the middle of the inner ring and air isbeing ejected in the middle of the inner ring. The outer ring amplifiesthe wake expansion, which produces the under-pressure driving themachine. The airfoils do not have an inner flow and in principle can bea plat or sail type airfoil. In this embodiment, air intake is shown atthe base of the tower, represented as M_(E). The tower continues intothe middle of the inner ring and air is being ejected in the middle ofthe inner ring. The outer ring amplifies the wake expansion, whichproduces the under-pressure driving the energy extraction.

This principle is exemplified in FIG. 10. The middle ring 1002 has airejected into the middle of the inner ring 1003, referred to as m_(e).Airflow 1001, may be represented by m_(r)=U_(∞)*ρ*A. The outer ring 1005provides the wake expansion into the expanded ring 1004 (m_(r)+m_(e)).Other variations of the system of the present invention are shown inFIG. 11 and FIG. 12. In these particular embodiments a perforatedinternal is implemented to distribute airflow from the internals, theplenum, to the external evenly over the low pressure part of thestructure. FIG. 11 provides for a radial expansion approach, where aradial shaped aerodynamic assembly having an inner aperture 1102,wherein airflow 1101 passes into the inner aperture 1102, whereinperforations 1103 are present distributing airflow out of the plenum1108 and into the aperture, causing the flow of air passing into theintake 1105 and into the channel 1107. An electrical generator 1106 islocated within the channel for energy extraction. Additionally, a choke1108 may be utilized in managing fluid flow in the channel.

FIG. 12 presents an alternative embodiment 1200 having a perforatedinternal 1202 having a plenum positioned within an upper aerodynamicassembly 1203 and a lower aerodynamic assembly 1204. A gap 1203 allowsfor fluid flow 1205. The pressure differential as described in thepresent invention causes the fluid flow into the plenum 1201, into thegap 1203, and outward. Energy extraction means may be dispatched intothe plenum of the upper and lower aerodynamic assemblies 1203, 1204.

As discussed herein, there is generally a desire to integrate windturbine renewables in buildings. Several problems with this persistincluding vibrations and maintenance in difficult conditions.

The power produced by the suction of the array, can either be used togenerate power from one or more generators. However, it would be moreprudent to use the suction generated directly as part of the airconditioning system, providing fresh air intake to the building withouthaving to use conversion to electrical systems. In this case, an airduct switch system must be in place to switch between this system andthe regular system depending on the wind directions.

FIG. 13 shows a version taking advantage of the present invention andcombining multiple elements. One or more airfoils 1301 are presented asan array, allowing for mirrored arrangement as well as a trailing edgeassembly 1304. Airflow 1305 passes into the assembly and between theairfoils 1301 to amplify the pressure differential 1303. Furtheramplification may occur utilizing trailing edge. Fluid flow coming (fromleft) 1305 with both air jets and trailing edge blowing is used. Fluidis coming into the interior of the blades, sucked up from the basethrough one or more channels (not shown).

FIG. 14 presents an exemplary embodiment of an asymmetrical layout ofthe system of the present invention 1400 having one or more directionalairfoils 1401 facing the fluid flow 1404 which utilize two effects: theout of the plenum jetting 1402 and the trailing edge effect 1403 used incombination, increasing the pressure differential.

In certain instances, an array system of the present invention will bemore efficient than a single or dual airfoil system. The array caneither be symmetrical, as shown in FIG. 13 or asymmetrical as shown inFIG. 14. A significant benefit of this arrangement is that when largeclusters are placed in farms, wakes are manipulated not to be straightdownstream. Thereby a farm of devices (wind or water) can potentially beoptimized.

In another embodiment of the staggered array systems, the airfoils canbe rotated around the vertical axis and adjustments to the wind axis canbe made. In another embodiment the whole staggered block can be rotatedas the two airfoil system shown in FIG. 14.

As discussed with the previous building applications, the skyscraper maysimply be replaced with a shallow base to be sunk on the ocean, lake orriver floor, so the device can be used as an ocean current energyextraction device. In the water application, the water pumping effect(similar to the air-condition effect) may be much more attractive thanthe electricity generation application.

The example below provides illustrative embodiments of the presentinvention. While various embodiments have been described for purposes ofthis disclosure, such embodiments should not be deemed to limit theteaching of this disclosure to those embodiments. Various changes andmodifications may be made to the elements and operations described aboveto obtain a result that remains within the scope of the systems andprocesses described in this disclosure.

Example

Computational fluid dynamics (CFD) results have been used to calculatedifferent configurations. FIG. 15 shows a two dimensional version ofsuch calculation. The airfoils are inserted into a large computationaldomain in order to avoid blockage, as such would artificially increasethe performance of the device in the calculations, such as normally donewhen investigating energy extraction devices (wind turbines). Flow isinjected from the hollow of the airfoils. Different configurations oforifice size, location and airfoil configuration have been investigatedusing this particular calculation method such as outlined in thetechnology description.

The results of two configurations is shown in FIG. 16A-B, where thepower extracted in Watt-per-meter airfoil and the corresponding powercoefficient has been calculated as a function of the pressuredifferential between the hollow of the airfoils and the ambientpressure. This pressure differential is controlled by the energyextraction and the design of the fan in the system. These two resultsshows that the system obviously is sensitive to the optimal designcombination, bearing in mind only two dimensional calculations have beenused for computational efficiency. A full three dimensional calculationor a model construct, would allow the flow from hollow to be swirlingand fold up into an air-jet. This is a significant advantage withrespect to the performance. FIG. 15 shows CFD calculation in twodimensions showing fluid flow between two opposite airfoils and a flowbeing injected into this stream from the hollow of the airfoils.

FIG. 16A shows result from CFD calculation of two different variant ofthat shown in FIG. 15. The y-axis is the power extracted in Watt permeter airfoil from the flow from the hollow of the airfoils as afunction of the pressure differential between the hollow and the ambientatmospheric pressure. The pressure differential will be controlled bythe energy extraction and essentially the fan design. FIG. 16B showsresults from the CFD calculation of the two different variants of thatshown in FIG. 15. The y-axis is the power coefficient extracted from theflow such as normally calculated for wind energy extraction devicesbased on the free stream velocity. The plot shows the sensitivity toconfiguration of the system to the performance.

The perforations as used herein can be arranged to amplify the system'sability to generate a low pressure; i.e. the more the airflow, the morethe ability to enhance the amplification. Perforations, which may besplits, air-jets, nozzles, holes, orifices, and the like enhance theself-amplification effect. Parallel, mirrored airfoils are the mostefficient way to further create centerline air pressure and can movethem around to change the characteristics of the system describedherein.

Those skilled in the art will recognize that the methods and systems ofthe present invention may be implemented in many manners and as such arenot to be limited by the foregoing exemplary embodiments and examples.Furthermore, the embodiments of methods presented and described in thisdisclosure are provided by way of example in order to provide a morecomplete understanding of the technology. The disclosed methods are notlimited to the operations and logical flow presented herein. Alternativeembodiments are contemplated in which the order of the variousoperations is altered and in which suboperations described as being partof a larger operation are performed independently.

REFERENCES

-   Gammak, Peter David, Nicolas, Frederic, Simmonds, Kevin John, (Dyson    Technology, Ltd.); WO2009030881(A1)—A Fan, 2009 Mar. 12.-   Okabe Masumi, Honjiyou, Shigeru (Tokyo Shibaura Electric Co.)    JPS56167897(A)—1981 Dec. 23.-   De Lisio, Salvatore, U.S. Pat. No. 2,488,467 (A)—Motor-driven fan,    1949 Nov. 15.-   Perdue, R. J., U.S. Pat. No. 2,784,556, Anemo-electric power plants,    March 1957.-   http://www.ewi.tudelft.nl/en/current/ewicon/-   http://sheerwind.com/technology/how□does□it□work-   Price, T, J. UK Large-Scale Wind Power Programme From 1970 to 1990:    The Carmarthen Bay Experiments and the Musgrove Vertical-Axis    Turbines, Wind Engineering, Volume 30, No. 3, 2006.-   Oliver, A. G., Wootton, L. R. W., Prats, J., Westergaard, C. H.,    Voutsinas, S. (1997) Wind turbine blades equipped with Air-jet    vortex generators: Full scale verification of blades optimized for    increased performance, EWEC, Dublin, October, 1997.-   Keen, E. B., A Conceptual Design Methodology for Predicting the    Aerodynamics of Upper Surface Blowing on Airfoils and Wings, Thesis,    Virginia Polytechnic Institute & State University, November 2004-   Delafond, F., Problems Concerning Automatic Connection of an    Aerogenerator to a Network (translation), Original: United Nations    Conference on New Sources of Energy, 1961, Proceedings Solar Energy,    Wind Power and Geothermal Energy, Rome, Aug. 21-31, 1961; Vol. 7,    Wind Power, pp. 390-394, Translation: National Aeronautics and Space    Administration, NASA TT F14,873, Washington, D.C. 20546, April 1973.-   Hutter, U, Past Developments of Large Wind Generators in Europe,    University of Stuttgart, approximately 1968.

1. An apparatus for energy extraction from a fluid flow comprising: a)an airfoil having an internal plenum, bounded by a first outer surfaceand a second outer surface, the first outer surface being solid and thesecond outer surface comprising one or more perforations in the secondouter surface allowing for fluid communication from the plenum to aspace surrounding the airfoil; b) a channel having an inlet and anoutlet coupled to the plenum, providing fluid communication between theinlet of the channel and the plenum; and c) one or more energyextraction devices in the channel between the inlet and the outlet;wherein an outer surface fluid flow across the outer surfaces of theairfoil is operable to cause a negative plenum pressure (Pi) relative toan ambient pressure (Pa) at the inlet of the channel, resulting in achannel fluid flow through the channel and the one or more energyextraction devices into the plenum, and out through the one or moreperforations in the second outer surface of the airfoil due to adifferential pressure between the Pi and the Pa, and wherein the one ormore energy extraction devices are operable for extracting energy fromthe channel fluid flow.
 2. The apparatus of claim 1, wherein the airfoilis configured to generate lower pressure regions near the one or moreperforations than the ambient pressure.
 3. The apparatus of claim 1,wherein each of the one or more energy extraction devices is selectedfrom a group consisting of: an electric generator and a hydraulic pump.4. The apparatus of claim 1, further comprising a motor operable toalign the apparatus or parts of the apparatus in response to a directionof the fluid flow.
 5. The apparatus of claim 1, wherein the one or moreperforations are arranged to amplify the differential pressure (Pi−Pa)as additional fluid flow exits the one or more perforations.
 6. Theapparatus of claim 1, wherein the airfoil comprises a first airfoil, theapparatus further comprising a second airfoil wherein the first airfoiland the second airfoil operably increase centerline pressure and fluidflow velocity to higher than ambient conditions.
 7. The apparatus inclaim 6, wherein the first outer surface and second outer surface of thesecond airfoil is mirrored from the first airfoil to operably increasethe centerline pressure and fluid flow velocity are higher than ambientconditions.
 8. The apparatus in claim 1 further comprising an actuatedchoke operable to regulate the maximum power of the fluid flow.
 9. Theapparatus of claim 1, wherein the airfoil is mounted onto a buildingstructure.
 10. The apparatus of claim 9, wherein the energy extractiondevice is mounted at a level below a roof of the building structure andin fluid communication to the plenum of the aerodynamic assembly by thechannel.
 11. The apparatus of claim 1 wherein the airfoil is mountedunderwater.
 12. The apparatus of claim 1, further comprising ventilationlocated near a trailing edge of the second surface of the airfoilproviding fluid communication from the plenum to the space surroundingthe airfoil and wherein the ventilation is operable in connection withthe one or more perforations to generate increased pressure differential(Pi−Pa).
 13. A method of extracting energy from a fluid flow comprising:a) positioning an airfoil having an internal plenum bounded by a firstouter surface of the aerodynamic assembly and a second outer surface,the first outer surface being solid and the second outer surfacecomprising one or more perforations allowing for fluid communicationfrom the plenum to a space surrounding the airfoil; and b) flowing fluidthrough a channel having an inlet and an outlet coupled to the plenumand in fluid communication with the inlet of the channel and the plenumand comprising one or more energy extraction devices in the channelbetween the inlet of the channel and the outlet of the channel; whereinan outer surface fluid flow across the outer surface of the airfoilcauses a negative plenum pressure (Pi) relative to an ambient pressure(Pa) at the inlet of the channel, resulting in a channel fluid flowthrough the channel and the one or more energy extraction devices intothe plenum, and out through the one or more perforations in the secondouter surface of the airfoil due to a differential pressure between thePi and the ambient pressure (Pa), and wherein the one or more energyextraction devices are operable for extracting energy from the channelfluid flow.
 14. The method of claim 13, further comprising arranging theairfoil to generate lower than ambient pressure regions near the one ormore perforations than the ambient pressure.
 15. The method of claim 13,further comprising extracting energy from the channel fluid flow by theone or more energy extraction devices selected from a group consistingof an electric generator and a hydraulic pump.
 16. The method of claim13, further comprising aligning the airfoil in response to a directionof the fluid flow.
 17. The method of claim 13, further comprisingarranging the one or more perforations to amplify the differentialpressure (Pi−Pa) as additional fluid flow exits the one or moreperforations.
 18. The method of claim 13 further comprising arranging asecond airfoil wherein the first airfoil and the second airfoil aremirrored to increase the centerline pressure and airflow velocity higherthan ambient conditions.
 19. The method of claim 13 further comprisingchoking the channel fluid flow velocity to regulate the maximum power ofthe fluid flow.
 20. The method of claim 13, further comprising mountingthe airfoil onto a roof of a building structure.
 21. The method of claim13, further comprising mounting the airfoil underwater.